How can I retrieve the last incremented control_number through Ajax instead of using local storage?

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There are different ways to retrieve the last incremented control_number through Ajax, depending on the specific implementation and technology stack being used. Here is one possible approach:

1. Create a server-side script that handles the generation and retrieval of the controlnumber. This script could be written in PHP, Python, Ruby, or any other language that your server supports. The script should have a function that generates the next controlnumber and saves it to a persistent storage (e.g., a database, a file, or a cache). The script should also have a function that retrieves the latest control_number from the same storage.

2. Use an Ajax function to call the server-side script and retrieve the latest controlnumber. The Ajax function could be written in JavaScript and triggered by a button or a form submission, or it could be run automatically when the page loads. The Ajax function should send a request to the server-side script and wait for the response. When the response arrives, the Ajax function should update the HTML page with the latest controlnumber.

Here is an example implementation using jQuery and PHP:

PHP script (controlnumber.php):

<?php
function get_control_number() {
    // Code to retrieve the latest control_number from storage
    $control_number = 1234; // Replace with actual code
    return $control_number;
}

function generate_control_number() {
    // Code to generate the next control_number and save it to storage
    $control_number = 1235; // Replace with actual code
    return $control_number;
}

if (isset($_GET['action'])) {
    $action = $_GET['action'];
    if ($action === 'get') {
        $cn = get_control_number();
        echo json_encode(['control_number' => $cn]);
    } else if ($action === 'generate') {
        $cn = generate_control_number();
        echo json_encode(['control_number' => $cn]);
    } else {
        echo 'Invalid action';
    }
} else {
    echo 'No action specified';
}

JavaScript function:

function getControlNumber() {
    $.ajax({
        url: 'controlnumber.php?action=get',
        type: 'GET',
        dataType: 'json',
        success: function(data) {
            $('#cn').text(data.control_number);
        },
        error: function(xhr, status, error) {
            console.log('Error retrieving control number: ' + error);
        }
    });
}

function generateControlNumber() {
    $.ajax({
        url: 'controlnumber.php?action=generate',
        type: 'GET',
        dataType: 'json',
        success: function(data) {
            $('#cn').text(data.control_number);
        },
        error: function(xhr, status, error) {
            console.log('Error generating control number: ' + error);
        }
    });
}

HTML code:

<div>Current control number: <span id="cn">Loading...</span></div>
<button onclick="getControlNumber()">Refresh</button>
<button onclick="generateControlNumber()">Generate</button>

This implementation assumes that the PHP script is located in the same directory as the HTML page, and that the server supports PHP scripts. When the user clicks on the "Refresh" button, the getControlNumber function sends an Ajax GET request to the controlnumber.php script with the 'action=get' parameter. The script responds with a JSON object containing the latest controlnumber, which is displayed in the HTML page. Similarly, when the user clicks on the "Generate" button, the generateControlNumber function sends an Ajax GET request to the same script with the 'action=generate' parameter. The script generates the next controlnumber and responds with a JSON object containing that value, which is displayed in the HTML page.